docs: def pair_bars(first: Histogram1D, second: Histogram2D, *, orientation: str = "vertical", kind: str = "bar", **kwargs):
      """Draw two different histograms mirrored in one figure.
  
      Parameters
      ----------
      first: Histogram1D
      second: Histogram1D
      color1:
      color2:
      orientation: str
  
      Returns
      -------
      plt.Axes
      """
      # TODO: enable vertical as well as horizontal
      _, ax = _get_axes(kwargs)
      color1 = kwargs.pop("color1", "red")
      color2 = kwargs.pop("color2", "blue")
      title = kwargs.pop("title", "{0} - {1}".format(first.name, second.name))
      xlim = kwargs.pop("xlim", (min(first.bin_left_edges[0], first.bin_left_edges[
                        0]), max(first.bin_right_edges[-1], second.bin_right_edges[-1])))
  
      bar(first * (-1), color=color1, ax=ax, ylim="keep", **kwargs)
      bar(second, color=color2, ax=ax, ylim="keep", **kwargs)
      ax.set_title(title)
      ticks = np.abs(ax.get_yticks())
      if np.allclose(np.rint(ticks), ticks):
          ax.set_yticklabels(ticks.astype(int))
      else:
          ax.set_yticklabels(ticks)
      ax.set_xlim(xlim)
      ax.legend()
      return ax